Abstract

The carrier transport through a resonantly coupled GaAs-AlAs superlattice is investigated by time-resolved electroluminescence (EL). This novel technique allows in principle to investigate carrier transport with a temporal resolution on the order of tens of picoseconds. Ultra-short current pulses are launched on a HF stripeline from an Auston switch which is triggered by femtosecond laser pulses with 1.9 MHz repetition rate. The amplitude of the electric pulses can be adjusted by the bias voltage. The current pulses propagate on the stripeline towards a 120 µm mesa pin diode, which is connected by gold wires. The intrinsic region of the pin diode is formed by a 40 period, weakly coupled superlattice with 21 nm GaAs quantum wells and 2.5 nm AlAs barriers. The electric pulse injects electrons and holes into the superlattice, which move by tunneling through the superlattice. Radiative recombination between electrons in the lowest conduction subband Cl and holes in the highest valence subband H1 gives rise to C1H1 emission around 1.52 eV. The recorded EL is temporally and spectrally resolved by a single-shot streak camera system with 50 ps time resolution.

© 1996 IEEE